Little Thieves by Margaret Owen
Vanja Schmidt knows that no gift is freely given, not even a mother’s love–and she’s on the hook for one hell of a debt. Vanja, the adopted goddaughter of Death and Fortune, was Princess Gisele’s dutiful servant up until a year ago. That was when Vanja’s otherworldly mothers demanded a terrible price for their care, and Vanja decided to steal her future back… by stealing Gisele’s life for herself.
The real Gisele is left a penniless nobody while Vanja uses an enchanted string of pearls to take her place. Now, Vanja leads a lonely but lucrative double life as princess and jewel thief, charming nobility while emptying their coffers to fund her great escape. Then, one heist away from freedom, Vanja crosses the wrong god and is cursed to an untimely end: turning into jewels, stone by stone, for her greed.
Vanja has just two weeks to figure out how to break her curse and make her getaway. And with a feral guardian half-god, Gisele’s sinister fiancé, and an overeager junior detective on Vanja’s tail, she’ll have to pull the biggest grift yet to save her own life.